Panel Ponders PLC Future at Joint ISA Sections Meeting

Is the PLC dead or alive? This was the main question debated by members of ISA's Chicago and Will-DuPage county sections during a Jan. 13 technical dinner meeting and panel discussion. The panel included representatives of PLC, DCS, and PC-based control manufacturers, such as Fisher-Rosemount (Austin, Tex.

Some participants thought very few PLCs will be sold five years from now. They reasoned that PCs' increasing penetration into almost every area of modern life will make them so common that control engineers will use them without hesitation.

However, other panelists added there are still many hard-wired relay control installations running today, even though PLCs have been accepted in manufacturing for years. Logically, they concluded that PLCs will also be around for many years.

The panelists generally agreed their markets and technology are being driven by users' needs for easily engineered, inexpensive systems that have smaller components, as well as users' desires for open systems. For instance, current technology often makes adding third-party components and software to control structures easier for users. However, this is both a threat and an opportunity for control system vendors because they must rely on buyers to understand the risk involved with mixing different vendors' components in the same control system.

With the proliferation of high-speed networks in factories, PCs that can handle large amounts of data and enable excellent communications will become even more necessary. The panelists added that PLC manufacturers have responded by adding PC coprocessors to handle these tasks. Meanwhile, PC software vendors have been working to take PC-based control downward to the device/logic level and upward to the DCS level. They're also constantly adding drivers to make it easier for users to add desired I/O devices to the system.

In conclusion, the panelists also agreed on implementation of IEC-1131. All have implemented at least part of the standard, and some are working to expand on it to offer users even better usability and flexibility. They projected a continued blurring of traditional distinctions among PLC, PC, and DCS, and added the result will be improved options for the control engineer.